Heavy metal pollution of aquatic sediments in the Le An River-P oyang Lake area

The sediment quality mapping of Cu．Zn．Pb and Cd in the<20μm fraction of surface sedi．ments ofthe Le An River·Poyang Lake area clearly proves that the mining activities ofDexing Copper Mine and nearby smaller Pb—Zn mines have already polluted the aquatic system to some extent．Although poilution indices of the Poyang Lake sediments are still close to background values，first results from sediment cores point to a definite trend of gradually increasing contamination．